One other question. If you are set up as a sole trader as well as having income from other employment, are your earnings from that employment taken into account in this respect, or ids it only the 7225 that comes from the business?
If your client has income from other employment, they can notify the HMRC by completing a CA72B Application for deferment of payment of Class 2 and/or Class 4 National Insurance contributions. This allows deferrment of the the self-employed contributions until after your client knows the actual amount of NIC due against the selfemployment. It just makes sure your client does not overpay as it is very difficult to get it back if it was not due.
I must admit over the years I have had lots of clients who have applied for and been given the deferment. It can be years before the HMRC get round to asking for the NIC due!